In a communication network, network nodes exchange data using network communication protocols. Internet Protocol (IP) is an example of a network communication protocol that facilitates packetized data communication between network nodes. In an IP-based network, each network node has an IP address. A packet sent between two network nodes generally includes a header with a source IP address and a destination IP address. The source address identifies the node that sends the packet, and the destination address identifies the intended recipient of the packet.
Legacy communication networks generally use 32-bit IP addresses according to IP Version 4 (IPv4). Wireless communication networks conforming to the TIA IS-835 standard, for example, rely on the IPv4 address space to identify wireless nodes ranging from network equipment to wireless communication devices (WCDs), such as mobile telephones. Dense mobile networks with millions of individually addressable nodes have resulted in rapid depletion of the 32-bit address space provided by IPv4.
With the limitations imposed by the IPv4 address space, network carriers are beginning to implement the 128-bit address space provided by IP Version 6 (IPv6). The vastly expanded address space of IPv6 permits wireless operators to easily support “always-on” services, in which case network nodes retain persistent IP address assignments. Some WCDs now support both IPv4 and IPv6 addressing for different applications. The use of IPv6 addresses is generally desirable for applications requiring long-lived connections.
Although IPv6 addressing is generally desirable, network equipment in many coverage areas will not immediately provide support for IPv6 during the transition from IPv4 to IPv6. Accordingly, the availability of network interfaces supporting IPv6 may vary as a WCD travels among different coverage areas.